Different synthetic and organic insecticides have been tested in the recent past years against Philaenus spumarius, the principal vector of Xylella fastidiosa, in olive orchards in the Apulia region (southern Italy). The results showed the need of additional research on new formulations and new testing to pursue a more sustainable and effective vector control. In this work, we tested the effects of kaolin on vector transmission and spread of the infections in olives. Experiments were carried out in an olive plot planted in April 2016 in the demarcated infected area, and consisting of 3-year-old olive plants of the susceptible cv Cellina di Nardò. The experimental controls included the non-treated plants and plants treated with imidacloprid on a calendar basis. Applications were performed for three consecutive years (2016, 2017 and 2018) starting in April or first decade of May until October. Treatments were repeated every 10-15 days or after major rain events. Visual inspections were periodically performed and, once a year, plants were sampled and tested for the presence of X. fastidiosa by real time PCR. Visually inspections recorded the presence of shoot dieback on the untreated plants since the first year after planting, and reached a percentage of 20% during the third year. Conversely, none of the plants treated with kaolin or imidacloprid have so far showed symptoms. Diagnostic tests carried out after three years, identified bacterial infections in approx. 40% of the untreated and kaolin-treated plants. This percentage decreased to ca. 18% in the control plants threated with imidacloprid, used in ours trials as positive control, but whose use practically is strictly in European level, due to the acute and chronic effects on honey bees. The overall results confirm the difficulties to achieve an effective reduction of the spread of the infections through the control of the adult spittlebugs, even when a relevant number of treatments per year (12-15) is applied. Strategies for reducing the juvenile populations combined with applications targeting the new emerged adults before they acquire and transmit the bacterium on olive trees should be emphasised.
Attempts to reduce the spread of Xylella fastidiosa in olives using kaolin applications
Cavalieri V;Zicca S;
2018
Abstract
Different synthetic and organic insecticides have been tested in the recent past years against Philaenus spumarius, the principal vector of Xylella fastidiosa, in olive orchards in the Apulia region (southern Italy). The results showed the need of additional research on new formulations and new testing to pursue a more sustainable and effective vector control. In this work, we tested the effects of kaolin on vector transmission and spread of the infections in olives. Experiments were carried out in an olive plot planted in April 2016 in the demarcated infected area, and consisting of 3-year-old olive plants of the susceptible cv Cellina di Nardò. The experimental controls included the non-treated plants and plants treated with imidacloprid on a calendar basis. Applications were performed for three consecutive years (2016, 2017 and 2018) starting in April or first decade of May until October. Treatments were repeated every 10-15 days or after major rain events. Visual inspections were periodically performed and, once a year, plants were sampled and tested for the presence of X. fastidiosa by real time PCR. Visually inspections recorded the presence of shoot dieback on the untreated plants since the first year after planting, and reached a percentage of 20% during the third year. Conversely, none of the plants treated with kaolin or imidacloprid have so far showed symptoms. Diagnostic tests carried out after three years, identified bacterial infections in approx. 40% of the untreated and kaolin-treated plants. This percentage decreased to ca. 18% in the control plants threated with imidacloprid, used in ours trials as positive control, but whose use practically is strictly in European level, due to the acute and chronic effects on honey bees. The overall results confirm the difficulties to achieve an effective reduction of the spread of the infections through the control of the adult spittlebugs, even when a relevant number of treatments per year (12-15) is applied. Strategies for reducing the juvenile populations combined with applications targeting the new emerged adults before they acquire and transmit the bacterium on olive trees should be emphasised.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
